The present invention relates generally to air conditioning systems for cooling and heating enclosures, such as are defined by domestic and commercial buildings. More particularly, the present invention provides a zone demand controlled dual source cooling and/or heating air conditioning system having an electronic controller system for mode selection and operation.
It is a principal feature of the present invention to provide a novel zone demand air conditioning system having a plurality of sources of beating and cooling, each being individually controlled for providing heating or cooling to meet the then current demand of a building structure and having a plurality of conditioned air supply ducts conducting conditioned air to individual zones of the building structure, with a thermostat for each zone and with an electronic controller circuitry for controlling zone blowers response to sensed zone temperature and for operation of the air conditioning system responsive to mode selection including, xe2x80x9ccoolingxe2x80x9d, xe2x80x9cheatingxe2x80x9d, xe2x80x9cfan onlyxe2x80x9d and xe2x80x9coffxe2x80x9d.
It is another feature of the present invention to provide a novel air conditioning system that may use various sources of cooling and heating equipment, such as heat pumps, chilled water, heated water, refrigerant compression and expansion systems, electric heating strips and combinations of the above and which are operable in cascade arrangement for operation according to thermal demand.
Briefly, the present invention, herein referred to as xe2x80x9cCascade Energy Saverxe2x80x9d (CES), relates generally to air conditioning systems which are employed for both heating and cooling of rooms within domestic dwellings and commercial buildings. More specifically, the present invention concerns a zone demand controlled multiple blower fan coil system which either is transfering heat to an evaporative coil circulating refrigerant R-22 or R 410a or transferring heat to a water coil or coils, whether separate coils, one being for chilled water and the other being used in conjunction with hot water, thereby being connected to equipment, whether split system heat pumps or chillers, boilers and pumps, and its electronic control system which employs state of the art solid state electronics installed so as to control the operations between the equipment, the CES and the space temperature of the conditioned chamber. Even more specifically, the CES integration of these assorted components to effectuate a fan coil that when properly applied to the application, the conditioned chamber is maintained at desired set point temperatures and the plurality of the conditioned chambers utilizing the conditioning effects whether cooling or heating, are maintained contemporaneously with accuracy and efficiency.
The inside spaces of building structures such as domestic dwellings and commercial buildings have in the past been cooled by a conventional air conditioning system having a heat exchanger installed externally to the building structure incorporating refrigerant heat exchange equipment whether air cooled or water cooled using coils, heat exchange blower and a compressor for achieving pressurized circulation of refrigerant such as freon R-22 or Puron R-410a with the effects of heat transfer being delivered to the conditioned chamber via the movement of refrigerant in the case of split system direct expansion system, or water lines circulating hot or cold water via pumps. Too, the typical air conditioning system also incorporates an air flow conduit system and a coil for heat exchange and a blower for circulating air through the conduit system to and from the inside space of the building structure. Typically the air conditioning system will also incorporate a condensed moisture collection and discharge system. For the purpose of heating, conventional building structures are provided with separate heat exchange systems which may employ electric resistance heaters, hot water coils or gas fired heating. Typically the blower of the heat dissipating exchanger of the air conditioning system will be large enough to also serve as the blower for circulating heat to and from the heat exchange apparatus in the case of heat pumps which extract heat from the ambient environment and through compression, transfer this heat to the conditioned chamber. The air conditioning system or the heating system may be manually selected or, as is typically the case, may be automatically selected by control circuitry having a thermostat for its sensing and control.
For a significant period of time alternative heating and cooling systems have been developed, typically referred to as heat pumps, which are typically electrically energized. A heat pump differs from conventional air conditioning systems only in the heat cycle. In the cool cycle the heat pump system incorporates an external condenser and internal evaporator each having heat exchange coils and blowers. In the cooling cycle the condenser unit circulates air across heat exchange coil through which refrigerant is circulated. The refrigerant gas absorbs the heat and the resulting cool air is circulated through an air supply and return conduit system that circulates the conditioned air to internal zones or spaces within the building structure. Simultaneously air that becomes heated by virtue of its presence within the zones of the building structure is circulated back through the coils for reheating the refrigerant which corresponds to a cooling effect to the air being circulated. The heat absorbed refrigerant is then circulated to the coils of the condenser located externally of the building structure and is liberated by the heat exchanger of the condenser into the external environment.
The heating cycle of the heat pump simply reverses the cycle. The heat is absorbed from the outside coils of the condenser and is exchanged via the coils of the internal evaporator so that heated air is circulated into the spaces of the building structure via the air circulation conduit system. Thus, the heat pump is a single air conditioning system that functions for both cooling and heating of the building structure, typically in response to thermostatic control. The process of exchanging heat by circulation of the refrigerant and having air to refrigerant heat exchange can also occur with refrigerant to water on both the evaporator and the condensor. If on the evaporator side, this process is referred to as reversed cycle chiller and if on the condenser side, it is referred to as water source heat pump and if from loops of piping in the ground it is referred to as ground source heat pumps.
It is typical for air conditioning systems to be designed and selected for peak load conditions and to employ a single air conditioning that is of sufficient capacity to accommodate the maximum peak load that will be experienced at any particular point in time. The block load as it is sometimes called is also the same as the building envelope load. Many times, the connected equipment, which is sized big enough to satisfy the sum of the individual zones, is larger than the peak building envelope load capacity requirement. The CES has by virtue of the multiple zones, the capability to be selected and sized for the peak building envelope load, though the number of zones served, may be summed up and represent a larger needed capacity. The CES will provide the required conditioning through the phenomenon called xe2x80x9cswingxe2x80x9d, as most tyically seen when a building has a large East exposure and West exposure. This circumstance is where the sum of the individual zones will exceed the peak building envelope load, but neither of the individual zones in and of itself will exceed the peak building envelope load. Therefore, by selecting the equipment capacity to be equal to or if by nominal sizes available larger than the peak building envelope load, the conditioned chamber will be satisfied. For this reason, air conditioning and heat pump systems will typically operate continuously under peak heat load conditions but at other times will cycle on and off as determined by thermostatic control. Maximum electric energy utilization occurs when the units are undergoing start up and initial refrigerant compression. Consequently, when a large unit cycles many times during each 24 hour period electrical energy utilization can be quite high. It is desirable therefore to provide system having the capability of accommodating a wide range of cooling and heating conditions and yet functioning at nominal electrical energy utilization. Likewise it is desirable to avoid the electrical spikes associated with starting a compressor, thereby minimizing both equipment wear and cost of electrical usage. It is also desirable to provide a system having the capability of substantially continuous operation of at least one stage of conditioning with other stages being in standby to thereby minimize start up cycling and thus provide for lower electrical energy requirements for handling a wide range of cooing and heating loads.
It is therefore a principal feature of the present CES invention to provide a novel conditioning system for domestic dwellings and commercial building incorporating Equipment which operates substantially at reduced electrical conditions to accommodate normal conditioning loads while the secondary capacity which is inherent to the unit operates intermittently to accommodate conditions of peak conditioning load. The CES invention uses (1. Split system heat pump units, typically sized to be one-half the total building envelope load capacity requirements, (2. Reversed cycle chillers with capacity controllers such as multi-speed compressors and hot gas bypass, (3. Chillers and boilers with pumps and a circulating system incorporating 2 way or 3 way motorized control valves, (4. Chillers with pumps and a circulating system incorporating 2 way or 3 way motorized control valves for cooling and the heating accomplished with electric resistance heating elements that are in the air stream of the CES whether in the upstream side of the blowers or in the discharge of the blowers as they are connected to the conduit air circulating system.
It is another feature of this invention to provide a novel system wherein the air conditioning equipment is segmented into roles of being designated as primary for substantially continuous operation under average conditioning load conditions and secondary air conditioning equipment being designated as the lag unit for simultaneous operation along with the primary air conditioning equipment under peak conditions of air conditioning load.
It is also a feature of this invention to provide a novel air conditioning system wherein primary and secondary equipment being employed can be switched from their current lead-lag role to that of lag-lead respectively to balance the equipment hours usage.
Briefly, the various objects and features of the present CES as an invention are effectively realized through a provision of an air conditioning system that is electronically interconnected for cascade operation when used in a heat pump arrangement and is provided with independent thermostatically controlled blowers for each of a multiple of zones that are designated within a domestic or commercial building structure. In this case, at least a pair of heat pumps are provided each of which is capable of accommodating average heat load conditions, so that one of the heat pumps is operational under average heat load conditions while the other heat pump is deenergized. When the heat load to the building structure reaches its peak conditions the second heat pump will become energized, so that the two heat pumps functioning together will effectively accommodate the peak heat load. Thus, the primary heat pump operates during most of each day to accommodate nominal heat load conditions and the secondary heat pump operates only during limited periods of heat load. The first heat pump will seldom cycle on and off during each day, thereby maintaining its electrical energy utilization at a nominal level since the high energy needs for cycling seldom occur. The secondary heat pump unit operates only under peak load conditions and thus it also cycles infrequently so that its electrical energy utilization is also at a nominal level. The first and second heat pumps are operated via an electrical control system incorporating a switch for reversing the primary and secondary heat pump designations, so that the primary heat pump becomes the secondary heat pump and visa versa to thereby maintain optimum service life of both heat pumps. The provision of the CES of the present invention includes the design of the refrigerant evaporator coil which as specific circuits, and are split 50/50 in such a way that both the air and the circulating refrigerant are cascaded. This means that the cooling effects are magnified to a certain extent as a result of the circuiting in such a way that there is greater dehumidification and greater sensible heat extraction. The refrigerant circuits are controlled from freezing through both simple temperature sensitive switches that break the control circuit serving the relays and contactors as well as more elaborate methods of multi-speed motored compressors, compressors with unloading capabilities for the intake reed valves if recipricating or bypass valves and sliders if constructed as a positive displacement compressor similar to scroll designs and also the hot gas bypass into the evaporator coil to maintain suction temperature and pressures.
Within the building structure there are designated comfort zones which are each provided with a conditioned air supply provided by an independent air supply blower for each zone. These blowers are driven by electric motors whether of the type that is constant speeds by multi-tapped core windings or by variable speed by virtue of controls affording variable frequency output from 0-60 hertz. Each of the comfort zones is also provided with a thermostat so that the air supply blower for that particular zone will operate only when the comfort load within that zone is different than the setting of the thermostat, whether heating or cooling mode and such that if the measured temperature is one degree away from set point, the CES will respond via the control logic of an electronic control system, typically mounted on an environmental control board (ECB) to energize blower fans, and equipment as required for creating multiple stages of cooling and heating. To the extent that the system is a heat pump system, both of the coil circuits of the evaporator coil will accommodate refrigerant from the primary and secondary heat pumps which are connected so that the effect of the refrigeration is in tandem, thusthe return air being drawn into the system and by the optional return air blower will be forced across the heat interchange surfaces of both of the coils to thus provide for heat exchange from the refrigerant passing through either or both of the coils. The multiple air supply blowers of the respective heat zones of the building structure each have their inlet side in communication with a conditioned air chamber or manifold so that cooled or heated air as the case may be is immediately available to each of the air supply blowers so that the conditioned air can be directed immediately to the thermal zone of necessity.
In the case of the the heat pump systems, each is provided with low and high conditions of heat pump operation and each is capable of operating so as to supply heated or cooled air to the air supply manifold depending upon the thermal conditions that are sensed by the respective thermostats. The systems that have air conditioning equipment that is comprised of chillers, reversed cycle chillers, boilers and pumps, with variable frequency drive (VFD) motor driven blowers, with ground source and water cooled heat pumps, there is logic in the firmware of the microprocessor on the ECB which causes sequencing, staging, cycling of fans, etc. to occur based on the zone thermostat""s configuration and set point.
Depending on the type of air conditioning equipment connected to the CES unit, each zone may act independently, such that one or more zones may call for cooling while one or more of the remaining zones may call for heating, these conditions occurring simultaneously.